1. Field of the Invention
This invention relates to apparatus and methods for breath collection and storage.
2. Description of the Prior Art
Recently there has been increasing interest in diagnostic and other measurements of the level of various components in exhaled breath. For example, it has been recognised that a measurement of the level of nitric oxide (NO) in exhaled breath can give a diagnostic indicator of the patient's lung condition, such as a degree of lung inflammation in asthma sufferers.
A difficulty in many of these measurements is that the breath sample may contain a very low level of the breath component of interest. For example, a healthy patient may have a breath NO level of about 7 ppb (parts per billion), while in an asthma sufferer the level may still be as low as under 100 ppb. These low levels and the need for clinical accuracy can mean that the measurement equipment is bulky, expensive and relatively fragile.
As a result, a two-stage technique has been developed, involving a remote collection of a breath sample, for example at a family doctor's premises or even in the patient's home, followed by later analysis of the sample at a central site such as a hospital, where the detection apparatus can be kept and maintained.
A polyethylene-lined collection and storage bag or reservoir has been proposed, whereby the patient exhales through a mouthpiece and detachable tube into an inflatable bag. The bag is then sealed. The breath sample can then be analysed later by puncturing the bag to transfer the stored sample into an analysis machine.